The present invention relates to a switch designed to be used as a circuit breaker as well as a medium voltage electrical switch.
A known load-break switch is described in U.S. Pat. No. 5,168,139 and comprises on the one hand a vacuum switch tube mainly comprising an insulating tubular case closed by two conducting end covers through which two coaxially opposite contact spindles pass having frontal contact faces, and on the other hand two switch contacts of the blade type, one of the breaking contacts being mounted in parallel with the vacuum switching tube, whereas the other switch contacts is mounted in series with the parallel circuit thus constituted. In operation, when the load-break switch is closed, and the two switch contacts are in a stable closed position, the vacuum interupter is kept open during operation of the switch. When the load-break switch opens, the vacuum interrupter contacts are first closed, then the parallel mounted breaking contact is opened, then the vacuum commutator contact is opened, and finally the second contacts arranged in series is opened.
However this device requires two separate control systems of the switches, which results in its dimensions being particularly large.
A multipole rotary switch is also known as described in FR 2,668,851, and which is formed mainly by a sealed revolution enclosure filled with a high dielectric strength gas, the internal circumference of the enclosure bearing, per pole, a stationary input contact, a stationary output contact and a stationary earthing contact. These contacts are spaced apart angularly and cooperate with a contact bridge in the form of a pivoting knife-blade supported by a rotary operating shaft extending in the axis of the enclosure. In this embodiment which does not use the vacuum breaking technique, the above-mentioned shaft can selectively occupy three positions, i.e. an open position, a closed position, and an earthed position.